1. Field of the Invention
The present invention relates in general to improvements in composite structures and in particular to methods and systems for controlling the transmission of radio frequency energy through composite structures. Still more particularly, the present invention relates to methods and systems for controlling the transmission of electrical energy through imperforate multi-layer fiber and resin composite structures without requiring apertures or discontinuities which might weaken the resultant structure.
2. Description of the Prior Art
Composite structures are increasingly utilized in modern aircraft, automobiles, pleasure craft and other applications in which high strength to weight ratios are desired or necessary. Complex air frame structures may be created having substantial strength in a predetermined axis by "laying up" multi-layer composite structures comprised of multiple layers of fibers, usually cloth or tape and selected resins which are thereafter cured utilizing heat and/or pressure. By aligning the axes of the fibers with the direction of the expected forces and stresses, a wide variety of lightweight, high strength structures are provided.
One problem which exists in the utilization of composite structures for aircraft is the necessity of predictably penetrating the composite structure with radio frequency energy for communications, navigation, radar, and electronic counter measure purposes. Heretofore the conduction of alternating currents through composite structural members has required apertures or other physical discontinuities within a composite structure to permit the penetration of electrical conductors. Composite structures which include such penetrations typically require local reinforcement to maintain structural strength, which adds to the cost, complexity and weight of the resultant structure. Attempts at radio frequency transmission through imperforate composite structures have been dramatically affected by the electrical characteristics of the composite material and the surrounding structures, and are thus not entirely predictable.
Thus, it should be apparent that a need exists for a method and system which permits the controlled transmission of radio frequency energy through an imperforate composite structure in a predictable and reliable manner.